Since we have firmware files, it's easy to create a user. Open the archive with the firmware, find the file flashforge_init.sh , Add the following lines, having previously changed username and password to your username and password:
USERNAME="USERNAME"
PASSWORD="password"
adduser --disabled-password --gecos "" "$USERNAME"
echo -e "$PASSWORD\n$PASSWORD" | passwd "$USERNAME"
It should turn out like this:
Next, install the USB flash drive into the printer, reboot, see how it is updated, reboot again, connect via Telnet to port 23, and rejoice.
Getting root (my way):
connect to printer using telnet, cat /etc/passwd, create file passwd in update archive, paste content, edit uid to 0 0 (screenshot)
Next, edit flashforge_init.sh and add cp $WORK_DIR/passwd /etc/passwd to copy passwd file to /etc/ directory
